iScience (Apr 2023)

Ultrasound-controlled acidogenic valorization of wastewater for biohydrogen and volatile fatty acids production: Microbial community profiling

  • Omprakash Sarkar,
  • Leonidas Matsakas,
  • Ulrika Rova,
  • Paul Christakopoulos

Journal volume & issue
Vol. 26, no. 4
p. 106519

Abstract

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Summary: The present study explored the influence of ultrasound on acidogenic fermentation of wastewater for the production of biohydrogen and volatile fatty acids/carboxylic acids. Eight sono-bioreactors underwent ultrasound (20 kHz: 2W and 4W), with an ultrasound duration ranging from 15 min to 30 days, and the formation of acidogenic metabolites. Long-term continuous ultrasonication enhanced biohydrogen and volatile fatty acid production. Specifically, ultrasonication at 4W for 30 days increased biohydrogen production by 3.05-fold compared to the control, corresponding to hydrogen conversion efficiency of 58.4%; enhanced volatile fatty acid production by 2.49-fold; and increased acidification to 76.43%. The observed effect of ultrasound was linked to enrichment with hydrogen-producing acidogens such as Firmicutes, whose proportion increased from 61.9% (control) to 86.22% (4W, 30 days) and 97.53% (2W, 30 days), as well as inhibition of methanogens. This result demonstrates the positive effect of ultrasound on the acidogenic conversion of wastewater to biohydrogen and volatile fatty acid production.

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